According to Article 223 of the Property Law, the following rights that the debtor or a third party has the right to dispose of can be pledged: (1) bills of exchange, checks and promissory notes; (2) Bonds and certificates of deposit. (3) Warehouse receipts and bills of lading; (4) Transferable fund shares and equity; (5) Transferable intellectual property rights such as the exclusive right to use a registered trademark, patent right and copyright; (6) Accounts receivable; (7) Other property rights that can be pledged according to laws and administrative regulations. According to the above regulations, it is an internal agreement between 4S stores to pledge your automobile certificate to the bank. You are three well-intentioned people, and their internal agreements must not be against you as a third person. Therefore, the act of "pledging" your automobile certificate by 4S is not protected by law. In addition, the automobile certificate is only the proof that the automobile is qualified and belongs to the special movable property of the automobile. It has no property value and cannot be transferred, so it cannot be "pledged". Therefore, when you go home, you have the right to ask the 4S store to bear the liability for breach of contract. You can discuss it with each other first. If negotiation fails, you can bring a lawsuit to the court. Litigation is risky, so prosecution should be cautious.